The supply and pressure control of mains water is a fairly complex operation and the adequacy of the supply and supply infrastructure varies from place to place. Conventionally the water system is arranged so that a minimum water pressure is maintained at all points in the system.
This is usually done with reference to the pressure prevailing at a number of critical points, that is to say at those points which are the highest above sea level or furthest away from the source of supply in the district concerned. However, there is invariably a considerable fluctuation in the demand for water throughout the day and also a considerable seasonal variation so that the maximum pressure is generally higher than the necessary minimum value.
A conventional system as previously described suffers from a number of problems, including the loss of significant quantities of water because of the poor condition of pipes in the distribution network, either due to their age or the materials of which they are constructed. The maintenance of a higher than necessary pressure level at a particular point increases the amount of water so lost and, additionally, exacerbates the deterioration of the system.
For a particular pipe network, it is known to include a regulating valve to maintain a predetermined pressure level at the valve location, and it is also known to include a mechanical control device to keep this pressure level to a minimum. However, once installed such mechanical control devices cannot be easily adjusted and thus if the characteristics of the system are altered in any way e.g. by the addition of further piping or supply requirements, then the controller can not take account of this and the pressure level is not maintained at an optimum value.